Prevalence of ESBL and AmpC genes in E. coli isolates from urinary tract infections in the north of Iran.

Beta-lactam resistance in Gram-negative bacteria, especially Escherichia coli, is a main clinical problem. It is often caused by the production of ß-lactamases, particularly extended-spectrum ß-lactamases (ESBLs) or AmpC enzymes. This study was undertaken to characterize ESBL and AmpC producers among Escherichia coli isolates from urine samples. During six months, 263 E. coli isolates were detected by standard biochemical tests. The isolates were screened for ESBL production by the double-disk synergy test using Ceftazidime (30 µg) and Cefotaxime (30 µg) disks and confirmed by combined disk diffusion test using Clavulanic acid. AmpC production was confirmed by an AmpC disk test based on filter paper disks impregnated with EDTA. The presence of genes encoding TEM, SHV, CTX-M, CIT, FOX, MOX, ACC, and EBC were detected by PCR. 263 E. coli isolates were selected for the combined disk (Ceftazidime, Cefotaxime, and Clavulanic acid) assay in the disk agar diffusion test. In the combined disk assay, among 263 isolates, 121 (46%) isolates were detected as ESBLs, and none of the isolates were AmpC producers. PCR performed on all ESBL producers and blaSHV, blaTEM, and blaCTX-M were detected in 42 (34.7%), 44 (36.4%), and 47 (38.8%) cases, respectively. Also, from 48 Isolates with zone diameters of less than or equal to 18 mm to Cefoxitin, 7 (14.6%), 4 (8.3%), and 9 (18.8%) cases contained MOX, EBC, and CIT genes, respectively. DHA, FOX, and ACC genes were not detected in any sample. Since pathogens evolve in the hospital setting, updating local data, such as this research, offers scientific evidence to improve the outcome of nosocomial infections.

Isolation and phenotypic and genotypic characterization of the potential probiotic strains of Lactobacillus from the Iranian population.

Among different causes of inflammatory bowel disease (IBD), the imbalance of the gut microbiome (dysbiosis) is one of the main reasons for the development of the disease. Probiotics are live microorganisms that can maintain gut microbiota by different mechanisms. We aimed to isolate and characterize the potential probiotic strains of Lactobacillus from the Iranian population. This cross-sectional study was conducted on faecal samples of 83 volunteer individuals living in Guilan Province, North Iran. The primary identification of Lactobacillus strains was performed by standard microbiological tests and confirmed by amplification of 16s rRNA specific primers. The acid and bile salt tolerance were assessed for all recovered strains. Also, the presence of 3 bacteriocins encoding genes was investigated by the PCR method. Totally, 42 samples were positive for Lactobacillus species. Acid and bile resistance assay showed that 67% and 33% of strains were resistant to acid and bile salt stress, respectively. Therefore, we found out that 28% of our Lactobacillus strains have the ability for resistance to acid and bile conditions. PCR results revealed that the prevalence of gassericin A, plantaricin S, lactacin bacteriocin genes were 16.6%, 12%, and 9.5%, respectively. Meanwhile, 5 out of 12 Lactobacillus strains that were resistant to acid and bile conditions contained one of the gassericin or plantaricin bacteriocins. We isolated 42 potential probiotic strains of Lactobacillus, of which the results of 5 strains were more promising and can be considered as potential probiotics sources for future functional products.

Characterization of virulence factors, antimicrobial resistance patterns and biofilm formation of Pseudomonas aeruginosa and Staphylococcus spp. strains isolated from corneal infection.

INTRODUCTION: Infectious keratitis is a serious ocular infection that can lead to severe visual impairment and blindness. Bacterial pathogens are responsible for nearly half of infectious keratitis cases. This study was performed to determine the virulence factors, antimicrobial resistance patterns, and biofilm formation ability of Pseudomonas aeruginosa and Staphylococcus spp. strains isolated from corneal infections. METHODS: A total of 56 corneal scraping samples were collected over 8 months. P. aeruginosa and staphylococcal strains were identified by phenotypic and genotypic methods. Determination of multidrug resistance was performed according to its definition of multidrug resistance (MDR). Detection of antimicrobial resistance genes and determinants of virulence were also performed using standard procedures. Biofilm formation ability of the isolates was determined by colorimetric microtitration plate assay and Modified Congo red agar (MCRA). RESULTS: In the present study, P. aeruginosa, MSSA, MRSA, MS-CoNS and MR-CoNS strains were isolated from corneal infections. Multidrug resistance was observed in 42.9% and 57.1% of P. aeruginosa and Staphylococcus spp., respectively. The most frequent virulence genes among P. aeruginosa strains were exoA and exoS (100%) followed by exoU (71.4%) and lasB (28.6%). All the P. aeruginosa isolates were biofilm producers and carried the algD gene (100%). All staphylococcal strains were negative for pvl gene amplification. Biofilm formation was also observed in 4 (57.1%) isolates. Both icaA and icaD genes were detected in the biofilm producers. CONCLUSION: Our results indicated that P. aeruginosa and Staphylococcus spp. were the most prevalent bacterial agents that cause corneal infections. However, their virulence traits and biofilm formation ability were noteworthy.

Epidemiology of toxic shock syndrome toxin-1 harboring Staphylococcus aureus obtained from clinical samples in Iran: A Systematic Review and Meta-analysis.

BACKGROUND: S. aureus strains, with the capability of producing toxic shock syndrome toxin-1 (TSST-1), are more likely to cause complicated infections. However, due to lack of comprehensive local data on the prevalence of TSST-1, we aimed to determine the prevalence of TSST-1 harboring S. aureus isolates in Iran. METHODS: A systematic search was performed by using PubMed and Scopus databases from papers published by Iranian authors from January 2000 to the end of March 2017. Then, 10 publications which were matched with inclusion criteria were selected for data extraction and analysis by Comprehensive Meta-Analysis Software. RESULTS: The overall prevalence of TSST-1 carrying S. aureus in Iran was 21.3% (95% CI: 7.9%-46.1%), ranging from 0% to 68%. Moreover, from the included studies, the pooled prevalence of TSST-1 producing MRSA isolates was estimated to be 25.2% (95% CI: 13.3%-42.5%), ranging from 0% to 69.8%. From those studies which showed the distribution of toxin-harboring S. aureus it was found that the skin and soft tissue, respiratory and bloodstream infections were the common sites of TSST-1 harboring S. aureus. CONCLUSIONS: In summary, it seems that emergence of MRSA strains leads to higher prevalence of TSST-1 carrying strains in the north of Iran. However, further research is required to elucidate the interplay between the outcome of diseases and TSST-1 producing strains, especially in our country.

Antibiotic resistance and frequency of class 1 integrons among Pseudomonas aeruginosa isolates obtained from wastewaters of a burn center in Northern Iran.

BACKGROUND: Pseudomonas aeruginosa, being responsible of a broad variety of infections, is considered an important nosocomial pathogen. The emergence of multiple-drug resistance among strains of P. aeruginosa appeared as a further public health concern. Due to the considerable ability of multiple-drug resistant P. aeruginosa strains to transmit themselves in the environment, we aimed to investigate the association of class 1 integrons with the antibiotic resistance profile of P. aeruginosa strains isolated from hospital wastewaters. METHODS: In this cross-sectional study, a total of 100 P. aeruginosa isolates were obtained from raw wastewater samples from February 2010 to January 2011 in a Teaching Burn Hospital in Guilan province. All isolates were identified as P. aeruginosa using standard microbiological tests. Antibiotic susceptibility was investigated using the disk diffusion method according to Clinical and Laboratory Standards Institute recommendations. All isolates were assayed for the presence of the class 1 integrons gene by PCR. RESULTS: Overall, 30 (30%) P. aeruginosa isolates were positive for the presence of class 1 integrons. The highest antibiotic resistance rates in both integron-positive and -negative isolates belonged to cephalexin and cephazolin, with 100% resistance. Amikacin and ciprofloxacin with the lowest level of resistance (13.3%) were the effective antibiotics against integron-positive isolates. The rates of MDR isolates were significantly higher among integron-positive isolates with 43.3% compared to negative isolates with 22.9% (P < 0.05). CONCLUSION: The results highlight the importance of class 1 integrons in multiple antibiotic resistance among P. aeruginosa isolates. Moreover, the spread of hospital derived wastewaters in the environment can be regarded as the origin of significant reservoirs for antibiotic-resistant pathogens.

Molecular epidemiology and characteristics of 16 cases with Stenotrophomonas maltophilia bacteraemia in pediatric Intensive Care Units.

BACKGROUND: Recently, Stenotrophomonas maltophilia has increasingly been reported as an important nosocomial opportunistic pathogen. Limited therapeutic options of S. maltophilia infections demand early identification and knowledge about the probable risk factors for controlling its spread. STUDY DESIGN: The present study aimed to investigate the risk factors and trend of antibiotic susceptibility, along with genetic analysis in bacteraemia cases at pediatric intensive care units (PICUs). METHODS: A total of 16 S. maltophilia isolates were obtained, during 4 months from August to November 2015, from blood cultures of patients admitted to PICUs at Nemazee teaching hospital, Shiraz, Iran. S. maltophilia isolates were identified by conventional tests and confirmed by specific PCR primers. Minimum inhibitory concentrations (MICs) were determined by the MIC strip test as described by the Clinical and Laboratory Standards Institute's (CLSI) recommendation. The genetic relatedness among the isolates was assessed by ERIC-PCR. RESULTS: All isolates of S. maltophilia were susceptible to ciprofloxacin, co-trimoxazole and colistin, and only 1 (6.2%) isolate was resistant against ceftazidime. The MIC50/MIC90 of ciprofloxacin, trimethoprim/sulfamethoxazole, colistin and ceftazidime was 0.25/0.38 mg/mL, 0.125/0.19 mg/mL, 0.25/0.38 mg/mL, and 2/4 mg/mL, respectively. Genotypic analysis of ERIC-PCR results revealed two distinct types of pattern. Interestingly, the only ceftazidime resistant isolate showed different patterns with other isolates. CONCLUSIONS: Our findings indicated the importance of routine surveillance in infection control, since early detection of pathogens prevented the spread of nosocomial infections and granted effectiveness to care practices. Moreover, the results suggest that the routine drug of choice for S. maltophilia was mostly active against clinical isolates in our region.

Emergence of Multidrug Resistance and Metallo-beta-lactamase Producing Acinetobacter baumannii Isolated from Patients in Shiraz, Iran.

BACKGROUND: Metallo-beta-lactamase (MßL) enzymes production is one of the most important resistance mechanisms against carbapenems in some bacteria including Acinetobacter baumannii. AIMS: This study was aimed to determine the antimicrobial susceptibility and the prevalence of MßL among carbapenem-resistant isolates of A. baumannii. MATERIALS AND METHODS: In this cross-sectional study from October 2012 to April 2013, 98 isolates were identified as A. baumannii using Microgen™ kits and confirmed by molecular method. These isolates were tested for antimicrobial susceptibilities by disk diffusion method according to the Clinical and Laboratory Standards Institute guidelines. Carbapenem-resistant isolates were further detected phenotypically by MßL minimal inhibitory concentration (MIC)-test strips, and subsequently positive MßL isolates were confirmed by polymerase chain reaction (PCR). RESULTS: Overall, 98% (96/98) of A. baumannii isolates were detected as carbapenem-resistant by MIC test. Highest sensitivity to the tested antibiotic with 42.9% (42/98) was observed to colistin. Of 96 carbapenem-resistant isolates, 43 were phenotypically positive for MßL; out of 43 isolates, 37 were confirmed for the presence of MßL genes by PCR. CONCLUSION: The frequency of drug resistance among the clinical samples of A. baumannii isolated in our study against most of the antibiotics was very high. Moreover, all MßL producing isolates were multidrug resistance. Therefore, systematic surveillance to detect MßL producing bacteria and rational prescription and use of carbapenems could be helpful to prevent the spread of carbapenem resistance.

Colonization Rate and Risk Factors of Vancomycin-Resistant Enterococci among Patients Received Hematopoietic Stem Cell Transplantation in Shiraz, Southern Iran.

BACKGROUND: Infections caused by antimicrobial-resistant bacteria are associated with increased mortality and health care costs. Enterococci have been recognized as a clinically important pathogen in hospitalized patients. Vancomycin-resistant enterococci (VRE) infections cause significant morbidity and mortality among patients undergoing transplantation. OBJECTIVE: To identify epidemiology of VRE colonization and related risk factors among patients with hematological malignancies after hematopoietic stem cell transplantation (HSCT). METHODS: This cross-sectional study was performed on 42 patients who underwent bone-marrow transplantation between July 2013 and March 2014. A stool sample was taken from each patient 3-5 days after transplantation and cultured on appropriate media. Suspected colonies of enterococci were detected to species level by their culture characteristics, biochemical reactions and molecular features. VRE were confirmed via phenotypic and genotypic methods. RESULTS: VRE were detected in 14 (33%) of studied samples. 10 (71%) of the detected VRE isolates were identified as high level vancomycin-resistant E. faecium with minimum inhibitory concentration (MIC) of ≥256 µg/mL of vancomycin; 3 isolates were E. galinarum and 1 was E. casseliflavus with an MIC of 8-16 µg/mL. VanA was dominant phenotype and all VRE isolates with high-level of vancomycin resistance had vanA gene. VRE isolation was mostly observed in patients with acute lymphoblastic leukemia (ALL) than other diseases. Moreover, antibiotic prophylaxis and hospitalization were independent risk factors for acquisition of VRE after transplantation. CONCLUSION: We found high level of vancomycin-resistance in E. faecium isolates obtained from HSCT patients. The vancomycin-resistant isolates of E.faecium had vanA and/or simultaneously vanB genes.